The present invention relates to a voltage converter scheme, and more particularly to a constant on-time pulse width control-based apparatus used in a voltage converter and including fast transient response capability and flexibility for adaptively adjusting the on-time pulse width in response to the occurrence of a transient event.
Generally speaking, a conventional constant on-time controller is usually limited by small ESR (equivalent series resistor) of its output capacitor. The conventional controller cannot effectively reflect/detect output voltage ripple to detect or response to the occurrence of a transient event due to that the ESR is too small. Some conventional schemes are proposed to improve this problem. However, a part of these conventional schemes still cannot effectively detect or response to the occurrence of the transient event. In addition, another part of the conventional schemes may adopt a certain fixed value to set the on-time pulse width. However, it is not flexible to adopt the fixed value to set the on-time pulse width since the event of transient variation is not always the same.